Continuous casting of metal



July 17, 1951 J. v. GIESLER EI'AL CONTINUOUS CASTING OF METAL Original Filed July '7, 1947 5 Sheets-Shed 1 I I R91.

INVENTORS r m a .@e f 8 V E 7mm w I N m T T A July 17, 1951 J. v. GIESLER r AL 2,560,539

I CONTINUOUS CASTING 0F Original Filed July 7, 1947 v 5 Sheets-Sheet 3 v mmvr'oxs Je'amVGie-slef Hug'kEf/Gzaernm.

Arromvsvs July 17,1951 J. v. GIESLER ETAL' 2,560,639-

CONTINUOUS CASTING 0F METAL Original Filed July 7, 1947 5 Sheets-Sheet 4 INVHVTORSQ Jean. V. Giesl er BY Hugh E. lfizsermqn. nmm lhaow 7W July 17, 1951 J. v. GIESLER EI'AL 2,560,639

commuous CASTING OF METAL Original Filed July 7, 1947 5 Sheets-Sheet 5 .M mg g mvmibks 'J'ean. V. Gz'eslgr HugkEIfisez-maw.

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Patented July 17, 1951 CONTINUOUS CASTING OF METAL Jean V. Giesler and Hugh E. Kaserman, Knoxville, Tcnn., assignors to Robertshaw-Fulton Controls Company, Knoxville, Tenn., corporation of Delaware Original application July 7, 1947, Serial No.

759,360. Divided and this application December 13, 1948, Serial No. 64,966

4 Claims.

This invention relates to the continuous casting of metal and more particularly to an apparatus for such continuous casting, this application being a division of our application Serial No. 759,360, filed July 7, 1947, for Continuous Casting of Metal.

Heretofore various processes and apparatus have been proposed for the continuous casting of metals. In some of these molten metal has been .introduced into a stationar cooled mold and continuously withdrawn from the mold by mechanical means. In others molten metal has been introduced between moving molds and the resul ing ingot discharged through an opening between the moving molds. Various means have also been employed to adjust the speed of the ingot with respect to the rate of pouring of the molten metal so that the ingot is cooled and hardened before being withdrawn from the mold. Some of these controls employ photoelectric eyes infiuenced by the light emanating from the congealing metal in the hardening zone to regulate the speed of withdrawal of the ingot. Others employ for this purpose electrical contacts actuated by the level of the molten metal in the mold, and still others utilize the torque required to drive the moving molds to regulate the speed of emission of the ingot. All of these prior processes and apparatus are subject to disadvantages and "uncertainty of operation with consequent undesirable structural defects in the ingot. g

It is accordingly an object of this invention to provide a novel apparatus for the continuous casting of metal which is not subject to the uncertainties and disadvantages of operation of prior proposed devices and which will produce ingots of uniform structural characteristics.

Another object of this invention is to provide a novel apparatus for the continuous casting of metal in which the metal is cast between vertically disposed continuously moving molds and withdrawn as an elongated ingot of relatively small cross sectional dimension in at least one direction.

Another object of this invention is to provide such a novel apparatus in which novel means are employed to regulate the speed of the molds with respect to the rate of pour of the molten metal.

Other and further objects will become apparent as the description of the invention proceeds. 7

One embodiment of the present invention is shown in the accompanying drawings and described hereinafter to illustrate apparatus coming within its scope, but it should not be construed as defining the scope of this invention, as reference should be had to the appended claims for this purpose.

In these drawings,

Fig. 1 is a front view of one embodiment of our novel casting machine;

Fig. 2 is a side view of the embodiment of Fig. 1;

Fig. 3 is a side view of a part of Fig. 1 showing the mold plates removed in part to illus-' trate the novel mold construction;

Fig. 4 is a view of part of Fig. 1 with certain elements omitted for clarity;

Fig. 5 is an enlarged detail of a part of Fig. 1 showing the novel, arrangement of electrical contacts;

Fig. 6 is an enlarged detail of a part of Fig. 1 showing the novel means employed for starting formation of the ingot and for counterweighing the same;

Fig. 7 is an enlarged sectional view of the pouring spout shown in Fig. 1; and

Fig. 8 is a circuit diagram of a novel relay circuit for use with the embodiment of Fig. 1.

In the accompanying drawings, in which like reference numerals designate like parts, the machine is mounted over a pit in into which the ingot moves from the molds. Pit 10 may be of any suitable size and depth depending upon the length of the ingot to cast. It is of course apparent that instead of using a pit the entire machine can be elevated to allow an ingot of suitable length to move from the molds. As shown, however, beams II are secured to the top of pit l0 and support machine base elements l2. Secured to base elements 12 are vertical frame members 13 and I4 extending parallel to each other. Bearings l5 and iii are secured to frame member 13 and member M has aligned bearings I! and I8 secured thereto. A shaft I9 is mounted for rotation in bearings l5 and I1 and is driven by worm gear suitably mounted thereon. A shaft f2| is mounted for rotation in bearings l6 and I8 and has suitably secured to it a brake drum 22 engaged by brake band 23 adjustably mounted on frame Id at 24.

Sprocket wheels 25 and 26 are mounted on and secured to shaft is and sprocket wheels 2'! and 28 are mounted on and secured to shaft 2|. and 21 and a second chain is mounted upon sprockets 26 and 28. A plurality of mold forming bars 3| are suitably secured to chains 28 A chain 29' is mounted upon sprockets 25 3 and 39 for movement therewith and for limited movement with respect thereto.

As seen in Fig. 1, a similar mechanical arrangement is provided to support and carry a plurality of mold forming bars 32 parallel to and spaced from mold bars 3| in the mold forming area. This mechanism includes bearings 33 and 34 secured to frame It, corresponding bearings not shown being carried by frame I3, and shafts 35 and 36 are mounted for rotation in these bearings. Shaft 35 has worm gear 31 secured thereto and shaft 36 has brake drum 39 mounted thereon and engaged by brake band 39 which is adjustably mounted at 49 on frame I9. A sprocket 4| is mounted on shaft 35 and spaced from sprocket 4| and mounted on shaft 35 is a second sprocket not shown. Shaft 38 supports a similar pair of sprockets one of which is shown at 42. A pair of chains engage the corresponding sprockets, one of which, chain 93,- engages the sprockets 4| and 42, the other chain not being shown, and as before referred to a plurality of mold forming bars 32 are secured to these chains for movement therewith and for limited movement with respect thereto.

Frame I3 also carries bearings 45 which rotatably support a shaft 46. Worms 41 and 48 are mounted on shaft 46 and engage worm gears 29 and 31 respectively. A pulley 49 is also secured to shaft 46 and is driven by belts 59 and 59 and gear ratio changing device 89 as will more fully appear hereafter.

A mold side member is supported between the mold bars 3| and 32 in the mold forming area, as by brackets 52 and 53 secured to frame I4, said side member 5| being of a cross sectional dimension corresponding to the spacing between mold bars 3| and 32. Said mold bars 3| and 32 are in sliding engagement with the opposite faces of said side member 5| and are held against said member 5| by auxiliary frame members 52' and 53' (Fig. 4). Member 5| is hollow as shown at 54 (Fig. 3) to receive cooling water admitted at 55 and withdrawn at 56, and is provided with an aperture 51 to receive a suitable pouring spout 58. Aperture 51 is located approximately to the length of the adjacent reaches of the mold bars 3I and 32 from the top of their coming into parallelism.

A similar side member 59 (Fig. 5) at the opposite side of the mold cavity is supported between the mold bars 3| and 32 by brackets secured to frame I3, and the mold bars 3| and 32 are held in sliding engagement with said member 59 by auxiliary frame members not shown but identical with members 52' and 53'. Side member 59 is also hollow and cooling water is admitted thereto at 69 and withdrawn at 6|. members 5| and 59 are not parallel but diverge slightly from top to bottom for purposes to be explained hereafter. Side members 5| and 59 with mold bars 3| and 32 sliding over them therefore define a mold cavity of more or less re'ctangular shape and of small cross sectional dimensions as compared to its length.

As seen in Fig. 7 spout 58 is a more or less rectangularly shaped open box of any suitably heat resistant material provided with a nose 62 to fit snugly in aperture 51 and with an inwardly extending partition 63 having an under surface 64 substantially parallel to the bottom of spout 58 and an upper surface 85 arranged at an angle thereto.

Mold bars 3| and 32 are surface conditioned before moving to the mold forming area by air jets Side 66 which dry them, by rotating brushes 61 driven by motor 68 and belts 69 and 19 which clean them, and by sprays 1| which coat them with suitable lubricating material. Said brushes 61 are journaled for rotation in frame extensions 12. The sprays 1I receive their lubricant from reservoirs 13 through 14. Air under pressure is Supplied to sprays 1 I through pipes 15 and the lubricant in reservoirs 13, graphite and kerosene being preferred, is kept mixed by air jets 1B. The area of bars 3| and 32 being sprayed may be, provided with a shield 11 so that the lubricating spray will not be deflected. The mold bars 3| and 32 may be cooled in the mold forming area by any suitable number of water jets 18 spraying cooling water directly upon the backs of bars 3| and 32. If desirable these jets may be replaced by cooling manifolds of any suitable design in direct contact with the backs of bars 3| and 32.

Main machine motor 19 drives through any suitable variable gear ratio changing device 89 which in turn drives belt 59 through additional speed reducing gearing or belts as desired and generally indicated at 59'. Gear ratio changing device 89 is driven by a three phase motor 8| driving pulley 82, belt 83 and pulley 89 secured to the shaft 85 for operating the gear ratio changing mechanism. Cable 86 leading from relay housing 81 supplies motor 8| with current. Current is supplied to motor'19 through cable 88, fuse box 99, switch 99 and cable 9|. Motor 68 is supplied with current from fuse box 89 through cable 92, switch 93 and cable 94.

Water is supplied to the sprays 18 and mold side members 5| and 59 are supplied with water by pipe leading from any suitable source of water. Pipe 96 supplies air under pressure to jets 69, sprays 1| and jets 16. Gas is supplied through pipe 98 to a burner 91 (Fig. 2) designed to cover spout 58 with flame during pouring to decrease oxidation of the molten metal and maintain the temperatures adjacent the aperture 51 at ap proximately pouring temperature. A suitable control panel 98 may be provided with manually operable valves 99 to regulate the supply of air, water and gas.

As shown in Fig. 6 means are provided for counterbalancing the weight of the ingot as it moves out of the mold, comprising pulleys I99 journaled for rotation on frame members I3 and I4 near the base of the machine and supporting cables I9I. ber I92 designed to receive the bottom edge of the casting as it leaves the mold area and to move in tracks I93 extending downwardly into pit I9. Cables I9I carry weights I94 at their ends and pass freely through a plurality of weights I95. Weights I95 are shown as of progressively increasing leng'th from bottom to top of pit I9 and are supported in spaced relation upon brackets I96 carried by racks I96. Oppositely disposed racks I96 diverge from bottom to top of pit I9 corresponding to the increasing lengths of weights I95. As the ingot leaves the mold it will engage tray member I92 and move it downwardly in pit I9 against the action of weights I94. As the ingot increases in length and weight, the weights I94, moving upwardly, will progressively pick up weights I95 thus counterbalancing the increasing-weight of the ingot. Knowing the size and weight of the finished ingot the weights I94 and I95 can be nicely calculated to obtain an exact counterbalance. After pouring is completed and the end of the ingot leaves the machine the ingot may be lifted from pit I9 by any Cables I9| carry between them a tray memsuitable means. As the ingot leaves pit I tray I02 moves upwardly under the action of weights I04 and I moving downwardly in pit I0 and weights I05 are returned progressively in order of their lengths from longest to shortest to their positions on brackets I06.

A dam member I01 is placed between mold bars 3| and 32 and mold members 5| and 59 just beneath aperture 51 before pouring is commenced to dam the mold area at the start of formation of the ingot as will more 'fully appear hereafter. Member I01 is provided with dovetail apertures I08 in which the molten metal of the ingot is cast to lock member I01 to the ingot. The length of member I01 is approximately that of the distance between members 5| and 59 but because members 5| and 59 diverge from top to bottom as above described member I01 is provided with block I99 resiliently urged by spring IIO into engagement with member 59 and its thickness is equal to the distance between the mold bars 3| and 32 in the mold cavity. Member I01 is easily removed from the cast ingot and may be used repeatedly.

Relay housing 81 contains a relay circuit shown diagrammatically in Fig. 9. This circuit includes a pair of electrodes III and H2 mounted in a frame I|3 supported by hooked IOds I4 designed to engage a cross member H5 of the machine frame to support electrodes III and 2 between the mold side members 5| and 59 and between the mold bars 3| and 32 in the mold forming area. Electrode II2 is'of such a length that it will extend to a point slightly below thebottom of aperture 51 and electrode III is slightly longer than electrode I I2. In a machine casting an ingot approximately seven inches wide and /2" thick this difference in length may approximate Wires III'and I|1 lead from electrodes III and H2 respectively to a suitable electric connector I I8 and from connector |I8 lead to the relay circuit. Wire H1 is connected to coil N9 of a solenoid operated switch I29 which is normally open. Coil I I9 is connected by wire I2I to wire I22 leading to induction coil I23. Coil I23 is grounded at I24. Wire I|6 leads to one side of coil I25 of a solenoid operated switch I26 which is normally closed. The other side of coil I25 is connected by wire I21 to wire I22.

coil I23 and is connected by wire I29 to wire I39 from a source of electric energy, and is connected by wire |3I to wire I32 from a source of electric energy. Wire E33 also leads from a source of electric energy. A wire I34 connects wire I29 with one side of switch I28 and wire I35 connects the other side of switch I20 to one side of coil I36 of a three contact solenoid operated switch I4I which is normally open. The other side of coil I35 is connected by wire I31 to one side of limit switch 238, the other side of which ,is connected by wires I39 and I40 to wire I3I.

Limit switch I38 is normally closed and is opened by the change speed mechanism 89 when it is moved to its position of greatest speed. For this purpose the visual speed indicator I4I' of mechanism 83 may be used to open switch I38 in any suitable way.

One side of switch I26 is connected by wire I42 to wire I34 and its other side is connected to one side of coil I43 of a three contact solenoid operated switch I44 which is normally open. The other side of coil I43 is connected to one side of limit switch I45 by wire I46. Limit switch I45 is normally closed and is opened by indicator MI when the change speed mechanism 80 is moved to its position of slowest speed. The other side of limit switch I is connected to wire I40.

Switch I44 is provided with three contacts I41, I48 and I49 and switch MI is provided with three contacts I50, I5I and I52. One side of contact I41 is connected to the corresponding side of contact I52 by wire I53 which is connected to wire I30. Corresponding sides of contacts I48 and I5I are connected by wire I54 which is connected to wire I32 and corresponding sides of contacts I49 and I are connected by wire I55 which is connected to wire I33. The other sides of contacts I41 and I50 are connected by wire I56 and then to one pole of three phase motor 8| by wire I51. The other sides of contacts I48 and I5I are connected by wire I58 and then by wire I59 to another pole of motor 8|. The other sides of contacts I49 and I52 are connected by wire I60 and then by wire IBI to the third pole of motor 8|.

With the mechanism and circuits of the present invention set up and connected as above described when an ingot is to be poured the several motor circuits are closed, gas jet 91 lit and air admitted to the several air jets. Motor 58 rotates brushes 61 to clean the mold bars 3| and 32, jets 66 dry the mold bars 3| and 32 as they pass by and jets 1| spray lubricant on the bars. Motor 19 drives through speed change mechanism 80, which in its slowest speed position, and mechanism drives worms 41 and 49 through belts 50 and 50. Rotation of worms 41 and 48 rotates worm gears 20 and 31 rotating shafts I9 and 35 which in turn rotate their associated sprockets and drive chains 29, 30 and 43 moving the mold bars 3| and 32 downwardly over mold side members 5| and 59. Rotation of chains 29, 30 and 43 also rotates their supporting sprockets on shafts 2| and 38 rotating these shafts and rotating brake drums 22 and 38 against the action of brake bands 23 and 39. The braking of shafts 2| and 36 forces the sprockets on shafts I9 and 35 to push the mold bars 3| and 32 downward through the mold forming area. As mold bars 3| and 32 are mounted for some movement relative to their supporting chains they are closely packed together in the mold area by this pushing action providing an almost continuous and uninterrupted mold surface producing an ingot having very smooth surfaces. When the mold bars 3| and 32 are in condition for pouring, i. e., preheated when required and properly cleaned and lubricated, dam member I01 is started down between the mold bars 3| and 32 and side members 5| and 59 and is held in position by the pressure exerted on it by mold bars 3| and 32. The machine is stopped as dam member I01 approaches aperture 51. Contacts II I and H2 are then hung down into the mold area from member I|5 as above described, the machine restarted and molten metal introduced into spout 58. During pouring spout 58 is kept almost level full of molten metal. This metal pours through nose 62 into the mold area and interlocks with dam I01 and congeals. Meanwhile dam I01 is moving downward with the mold bars 3| and 32 and the ingot is being continuously cast. Water cooling jets 18 may be turned on at any suitable time to prevent overheating of mold bars 3| and 32 or this may be done mechanically and automatically as the ingot leaves the bottom of the machine by causing the ingot to trip a valve I62 common to all the jets 18 (Fig. 4). As the ingot leaves the bottom of the machine it is picked up by tray member I02 and further downward movement of the ingot is counterbalanced by weights I04 and I05 as above described to prevent the weight of the ingot from increasing its speed of movement out of the mold cavity.

As indicated above, mold side members 5| and 59 diverge slightly from top to bottom. As the ingot is poured it congeals and takes shape in the area just below aperture 51. As the ingot moves downwardly this divergence reduces the friction between the ingot and the members 5| and 59 reducing the power required to drive the machine.

As pointed out above the change speed mechanism 80 is designed to normally run at its lowest speed ratio so that as pouring starts the mold bars 3| and 32 are traveling at their slowest possible speed. This speed is calculated slightly below the normal rate of pour from spout 58 so that the speed change mechanism 80 may regulate the speed of mold bars 3| and 32 to the rate of pour. If the rate of pour from spout 58 could be kept constant, no change of the speed of movement of mold bars 3| and 32 would be required, as the speed could be pre-set to equal the rate of pour. However, it is physically impossible to keep the pouring rate constant and as a result the height of the molten metal in the mold cavity will vary. As casting progresses suppose the rate of pour increases and molten metal contacts the lower elect-rode I I I. A circuit is then closed through the molten metal, electrode I I I, wire I I6, coil I25, wires I21 and I22, coil I23 and ground I24 and the current which is then induced in coil I23 passes to coil I25 and opens switch I26. If the height of the molten metal increases until electrode H2 is contacted then coil II9 is energized through the circuit comprising the molten metal, electrode II2, wire II'I, coil ||9, wire I2I, wire I22, coil I23 and ground I24 and switch I20 is closed energizing coil I36 through the circuit wires I30, I29, I34, switch I20, wire I35, coil I36, wire I31, closed limit switch I38, wires I39, I40, I3I and I32. Energization of coil I36 closes three contact switch MI and three phase motor 8| is energized and, driving through belt 83, continuously shifts speed changer 80 to a higher speed increasing the speed of movement of bars 3I and 32 and of the ingot. This speed increase moves indicator I4I away from limit switch I45 and allows limit switch I45 to close. The speed continues to increase until the speed of the ingot is such that the molten metal no longer contacts electrode H2, or until indicator I4I opens limit switch I38. When the molten metal no longer contacts electrode II2 coil H9 is de-energized, switch I20 opens, coil I36 is de-energized and switch I4| opens, de-energizing motor 8| and motor 8| stops. In either case the change speed indicator will remain at the speed setting at which the circuit was broken since breaking of the circuit stops motor 8| but does not reverse it. If this speed proves too fast and the level of the molten metal drops below contact III coil I25 is de-energized and switch I26 closes. As limit switch I45 is now closed coil I43 is energized through the circuit wires I30, I29, I34, I42, switch I26, coil I43, wire I46, switch I45 and. wires I40, I3| and I32, and switch I44 is closed energizing and reversing the three phase motor 8|. Speed change device 80 is now driven by belt 83 continuously to lower the speed ratio slowing down the speed of the mold bars 3| and 32 and of the ingot. Speed reduction continues until the level of the molten metal again contacts electrode III energizing coil I25 and opening switch I26 at which time switch I44 reopens and motor 8| stops or until limit switch I45 is opened by indicator I4I'. In either case the speed of mold bars 3| and 32 continues at the speed of the moment the circuit was broken since breaking the circuits stops motor 8| but does not reverse it until electrode H2 is again contacted by the molten metal. Since the difference between electrodes III and H2 is on the order of this speed change mechanism allows a most accurate maintenance of level of the molten metal in the mold resulting in ingots of very uniform characteristics.

As an example of the operation of this machine 180 pound runs of -20 brass have been cast at 2225 F. at an average rate of 40 inches per minute. The resulting ingots were approximately 12 /2 feet long, 7 inches wide and inch thick and exhibited unusually uniform crystalline char acteristics.

It will now be apparent that the present invention provides a novel apparatus for continuous casting of metals, which is of certain and uniform operation, by the pouring of the molten metal between vertical moving mold plates in a mold area of relatively small cross sectional dimensions as compared to its length, by regulating the speed of the molds with respect to the rate of pour of the molten metal, by counterbalancing the weight of the ingot as it issues from the mold area, by reducing the friction of the ingot in the mold, by damming the mold area at the start of pouring and by packing the mold bars together in the mold area to provide uninterrupted mold surfaces.

To those skilled in the art changes in or modifications of the above disclosed illustrative embodiment of the present invention will now be suggested without departing from the present inventive concept. Therefore to determine the scope of this invention reference should be had to the appended claims.

What is claimed is:

1. Means for controlling the, level of molten metal in the molding chamber of a continuous casting device having means for admitting molten metal to the molding chamber and means for removing solidified metal from the molding chamber comprising: variable speed means driving the metal removing means, said variable speed means including a control member movable through a range of controlling positions for setting the driving speed; a reversible electric motor for controlling the position of said control member, said motor being adapted to move said control member in a speed-increasing direction upon rotation of said motor in one direction and to move said control member in a speed-decreasing direction upon rotation in the opposite direction; a pair of electrodes projecting into the molding chamber, the lower extremity of one of said electrodes being below the lower extremity of the other of said electrodes; an electric circuit including said other electrode and the molten metal in the molding chamber for energizing said motor for rotation in said one direction when said other electrode is contacted by the molten metal; a second electric circuit for energizing said motor for rotation in said opposite direction; and electric means including a circuit through said one electrode and the molten metal for opening said second circuit when said one electrode is contacted by said molten metal.

2. Apparatus as claimed in claim 1 wherein the first said circuit includes switch means cooperable with said control member for precluding energization of said motor for rotation in said one direction while said control member is in its maximum speed position; said second circuit including switch means cooperable with said control member for precluding energization of said motor for rotation in said opposite direction while said control member is in its minimum speed position.

3. Means for controlling the level of molten metal in the molding chamber of a' continuous casting device having means for admitting molten metal to the molding chamber and means for removing solidified metal from the molding chamber comprising: variable speed means driving the metal removing means, said variable speed means including a control member movable through a range of controlling positions for setting the driving speed; a reversible electric motor for controlling the position of said control member, said motor being adapted to move said control member in a speed-increasing direction upon rotation of said motor in one direction and to move said control member in a speed-decreasing direction upon rotation in the opposite direction; a normally open electric circuit for energizing said motor for rotation in said one direction; means for closing said normally open circuit when the molten metal in the molding chamber rises to a preselected level, said means including a normally open switch, electrically operable means adapted when energized to close said normally open switch, an electrode in the molding chamber, and circuit means including said electrode and the molten metal in the molding chamber for energizing said electrically operable means when said electrode contacts the molten metal; a normally closed electric circuit for energizing said motor in said opposite direction; and means for opening said normally closed circuit when the molten metal in the molding chamber rises to a second preselected level, said last named means including a normally closed switch, electrically operable means adapted when energized to open said normally closed switch, a second electrode in the molding chamber having its lower extremity disposed below the lower extremity of the first said electrode, and circuit means including said second electrode and the molten metal in the molding chamber for energizing said last named electrically operable means when said second electrode contacts the molten metal.

4. Apparatus as claimed in claim 3 wherein the first said circuit means includes switch means cooperable with said control member for precluding energization of the first said electrically operable actuating means while said control member is in its maximum speed position; the second said circuit means including switch means cooperable with said control member for precluding energization of the second said electrically operable actuating means while said control member is in its minimum speed position.

JEAN V. GIESLER. HUGH E. KASERMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 394,695 Illingworth Dec. 18, 1888 589,081 Gritfith Aug. 31, 1897 1,108,693 Burkhardt Aug. 25, 1914 1,503,479 Coats Aug. 5, 1924 1,736,308 Davis Nov. 19, 1929 1,841,881 Davis Jan. 19, 1932 2,290,083 Webster July 14, 1942 FOREIGN PATENTS Number Country Date 869,178 France Oct. 29, 1941 217,286 Switzerland Feb. 2, 1942 

1. MEANS FOR CONTROLLING THE LEVEL OF MOLTEN METAL IN THE MOLDING CHAMBER OF A CONTINUOUS CASTING DEVICE HAVING MEANS FOR ADMITTING MOLTEN METAL TO THE MOLDING CHAMBER AND MEANS FOR REMOVING SOLIDIFIED METAL FROM THE MOLDING CHAMBER COMPRISING: VARIABLE SPEED MEANS DRIVING THE METAL REMOVING MEANS, SAID VARIABLE SPEED MEANS INCLUDING A CONTROL MEMBER MOVABLE THROUGH A RANGE OF CONTROLLING POSITIONS FOR SETTING THE DRIVING SPEED; A REVERSIBLE ELECTRIC MOTOR FOR CONTROLLING THE POSITION OF SAID CONTROL MEMBER, SAID MOTOR BEING ADAPTED TO MOVE SAID CONTROL MEMBER IN A SPEED-INCREASING DIRECTION AND TO MOVE SAID OF SAID MOTOR IN ONE DIRECTION AND TO MOVE SAID CONTROL MEMBER IN A SPEED-DECREASING DIRECTION UPON ROTATION IN THE OPPOSITE DIRECTION; A PAIR OF ELECTRODES PROJECTING INTO THE MOLDING CHAMBER, THE LOWER EXTREMITY OF ONE OF SAID ELECTRODES BEING BELOW THE LOWER EXTREMITY OF THE OTHER OF SAID 